This case study of an historian high school history teacher is an account of how differing views of the nature of history and historical knowledge influenced the teacher's teaching practice. The two discourse communities the teacher belonged to, that of the university where the degree was granted and that of the school community in which the teaching took place had distinct but interconnected and overlapping potential tensions for the teacher. The paper attempts to analyze the nature of the tensions resulting from the two groups and to explain how the teacher resolved them. The tensions are then tied to contemporary issues of reform in history education, the application of the new national history standards, and the preparation and professional development of history teachers. (EH)